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Langmuir circulation

White streaks in this lagoon are due to the Langmuir
circulation.

Langmuir circulation is a wind driven helix circulation in the ocean with
the axis almost parallel to the wind. Irving Langmuir discovered this
phenomenon after noticing windrows of seaweed in the Sargasso Sea in
1938.[1]

The circulation was found to be 15° to the right of the wind in
the northern hemisphere[2] and the
helix forming bands of divergence and convergence at the surface. At the
convergence zones floating seaweed, foam and debris will
concentrate and form the bands Langmuir noticed in 1938. At the
surface the circulation will set a current from the divergence zone
to the convergence zone and the spacing between these zones are of
the order 15–300 m. Below convergence zones narrow jets of
downward flow form and the magnitude of the current will be
comparable to the horizontal flow. The downward propagation will
typically be in the order of meters or tenths of meters and will
not penetrate the pycnocline. The upwelling will generally be less intense and
take place over a wider band under the divergence zone.

In an observation done at windspeeds of
14 m s−1 the horizontal spacing of the cells
were 20 m and maximum vertical velocity was
-18 cm s−1.